Wheelsets for railroad cars are usually comprised of an axle and two wheels. The wheels are pressed on to the axle shaft and are rigidly mounted so that both wheels turn exactly the same degree of rotation during operation. The wheelset assembly may be supported by journal bearings outboard of each wheel or the bearings may be located inboard of the wheels. The rigid assembly of the wheels on the axle and the lack of independent rotation of the wheels is the cause of slippage on the rail when the wheelset operates in curved sections of track. This slippage causes wear on the wheel treads and rails and is a prime cause of corrective maintenance on both the wheels and the track.
Efforts have been made to overcome the problems associated with the rigid assembly of conventional wheelsets by placing bearings between the axle and the wheel on at least one end of the axle to permit differential speeds of rotation of the wheels at opposite ends of the axle. In such cases, a hub is located on at least one end of the axle and a wheel is mounted on the hub or on the axle and its rotation with respect to the axle is facilitated by a bearing assembly. As discussed hereafter, electrical continuity from the two rails through the wheels and the axle is necessary for operation of signal devices or the like. This electrical continuity was established with the conventional railroad wheelsets wherein the wheels were rigidly fixed through opposite ends of the axle. However, with the advent of one of the wheels being mounted on the axle by means of a bearing assembly, the electrical continuity between the wheels was less than perfect. With the advent of non-metal bearings, the electrical continuity was not possible.
A typical signal device for a road crossing, for example which utilizes a crossing arm, flashing lights, and the like, derives electrical energy from any conventional source. A low voltage is imposed on a given dedicated length of rail on opposite sides of the signal, with the opposite rail being electrically connected to the signal whereupon the signal circuit is closed when the wheel assembly of a train initially moves onto the dedicated length of rail. The circuit is completed between the opposite rails through the wheels and axle of the train's wheel assemblies which allow the flow of energy therethrough to electrically connect the opposite rails.
It is a therefore a principal object of this invention to provide a railroad wheelset with independent rotation of wheels with respect to each other which will consistently retain the electrical continuity between the opposite wheels and the rails upon which they are supported.
A further object of this invention is to provide a wheelset with independent rotation of the wheels with respect to each other which can be used in existing truck designs without modification to the truck structures or the braking system.
A still further object of this invention is to provide a railroad wheelset which requires no additional maintenance than conventional rigid wheelsets after installation and during service.
A still further object of this invention is to provide a railroad wheelset with independently rotating wheels in which the differential action is made available with no decrease in safety or reliability.
A still further object of this invention is to provide a railroad car wheelset with independent wheel rotation which can be economically manufactured and applied to railroad cars of all types.
A still further object of this invention is to provide a railroad car wheelset with independent wheel rotation wherein the bearings for the independently rotatable wheel is comprised of a lubricating coating.
These and other objects will be apparent to those skilled in the art.